Sailors assigned to ships face a greater risk of sexual harassment and assault than servicemembers in any other branch of the military — particularly those assigned to Bremerton's two homeported aircraft carriers, according to a long-awaited Department of Defense study released Friday.

The report's release has been delayed for months, with military officials deciding to pause and review the study's methodology and language.

The study's findings are based on data collected from a RAND Corporation survey conducted in the summer of 2014. RAND received responses from more than 170,000 servicemembers about their experiences with sexual harassment and assault in the military.

Study: Aircraft carriers among most high-risk installations

The report does not break down the survey's results to include whether the assailant was a member of the military or a civilian, nor does it delineate whether the unwanted sexual behavior occurred on base or on a ship.

"In short, the estimates document the one-year prevalence of sexual assault for groups of personnel defined by their duty installation and duty major command; they do not document where the sexual assaults occurred or who committed the assaults," the study said.

The study found that a large proportion of unwanted sexual behavior occurred at the largest installations for each of the branches of the military. Installations with high-risk estimations often had large concentrations of young and junior-ranking personnel.

The study also determined that a servicemember's estimated risk of being harassed or assaulted depends on a number of factors related to their duty assignment, including their particular unit, command and installation.

"For instance, women could see their risk doubled or halved, depending on the installation or ship to which they are assigned," according to the report.

For the Navy, the study determined ships, particularly aircraft carriers, were among some of the most high-risk installations for both male and female personnel, while military medical facilities were assessed as some of the lowest-risk installations.

USS Nimitz, USS John C. Stennis in top 15 highest-risk

Naval Base Kitsap-Bremerton's two homeported aircraft carriers — USS Nimitz and USS John C. Stennis — were both ranked in the Navy's top 15 highest-risk installations for sexual assault risk posed to both male and female sailors.

Naval Hospital Bremerton, on the other hand, was among the 15 Navy installations ranked for having the lowest-risk rates for female personnel. No local commands ranked on the list of low-risk installations for male personnel.

A similar trend with aircraft carriers was seen fleet-wide. Of the top 15 high-risk installations for female sailors, 13 of them were determined to be ships or clusters of ships grouped together by those operating in the same zip code. Those ships included eight of the Navy's 10 active-duty aircraft carriers.

"Our model estimates that more than 10 percent of all women experienced a sexual assault at each of these high-risk installations over a one-year period, and more than 15 percent of all women were assaulted at two of them," the study states.

For male sailors, the dataset determined all but one of the top 15 highest-risk installations likewise were ships or clusters of ships. The ranking included five aircraft carriers.

"On one of these ships, we estimate that close to one in every 25 men was sexually assaulted in FY 2014, and more than 2.5 percent of men were assaulted on all of the ships in the highest-risk list," the report said, but it did not clarify which ship.

The study took it another step further and converted those risk estimations into a prevalence rate to determine the likely number of assaults at each installation that year.

By that calculation, the Nimitz is ranked ninth out of 10 installations with the highest rate of probable assaults, with an estimated 132 assaults in 2014.

Prior to this survey, the best glimpse into the systemic problems of sexual assault in the military came from the Department of Defense Sexual Assault Prevention and Response Office's annual report on the number of sexual assault investigations.

The most recent annual report on those investigations indicated a 10 percent increase in the number of investigated reports of sexual assault, up to 6,769 reports of sexual assault in 2017 from 6,172 in 2016. Officials attributed that bump to servicemembers' growing confidence in the system used to report such allegations.

However, the RAND report notes that dataset could offer an incomplete perspective of the issue "because sexual assault its known to be substantially underreported, and more so for men than women."

The RAND Corporation's study came with several caveats, including the omission of perspectives from reserve personnel on active-duty orders, civilian personnel and contractors. They were not surveyed, although they all would be present on the installations or work at the commands considered in the study.

Additionally, the data used in this study is now four years old.

"It is possible that some factors contributing to risk in some installations or commands in FY 2014 are no longer present today, in which case the estimates provided in this report would not accurately describe current risks," the study said. "Personnel may have moved; commanders may have changed; policies, procedures, and training programs may have evolved."

The study also only published risk estimates for commands that were able to provide a response sample size large enough where disclosing the names of those installations would not violate the privacy and confidentiality of participants who took the survey from smaller commands. As such, the results for many specific ships by name were left out of the published report.

Going forward, the study recommends using the report's findings to develop specialized training, prevention and response interventions at the installations and commands.